The miniaturization of electronic products is one of the primary tenets of technologic advance. Competitive advantage and the success of a product line largely hinges on the ability of a company to successfully provide products that are both increasingly functional and increasingly portable. As technology advances, it becomes increasingly possible to miniaturize electronic circuitry below human scale, with the result being that the interface (e.g., screens, keypads, cursor control devices) can come to limit the size of portable products. Therefore, as portable products enter this realm, the ergonomic quality and size of their input devices (such as keypads) will have a growing significance to product acceptance and success. Of special significance is the telephone keypad, because it has such importance worldwide as a fundamental communication and economic tool. International standards have been established, for example, for the minimum dimension between adjacent key switches to accommodate typical human fingertips. By “key” I mean an element, of an array of elements over a surface, which when struck produces an identifying output corresponding to the location of the element. The term “key region” includes, for example, a localized region having key-like behavior on a touch-screen and a localized region of a keypad formed by placing a membrane over an array of contact switches. A “keypad” is an array of keys or key regions and includes, among other things, a conventional keypad (such as is found on most telephones, calculators and such), a keyboard, and similar touch-sensitive arrangements implemented with a touch-screen or with demarcated zones on a membrane surface. While such a surface is commonly planar, it may also be curved.
Some of my earlier work has been directed at reducing the size of keypads through the development of keypads in which output keystrokes are determined both from individual switch activation and from the combined activation of adjacent switches. Some of my earlier work is disclosed in my U.S. Pat. Nos. 5,612,690 and 5,973,621, the entire contents of which are incorporated herein by reference. I refer to such keypads herein as “IACK” keypads, or Independent-And-Combination-Key keypads.
In this context, “independent keys” or “independent key regions” are elevated regions of a keypad surface with individual graphical elements, which provide a corresponding output when individually pressed. A “combination key” or “combination key region,” on the other hand, is a locally depressed region of an IACK keypad surface that provides a unique output as a consequence of the simultaneous or near-simultaneous manipulation of a set of two or more adjacent (e.g., diagonally adjacent or “kitty-corner”), independent key regions, typically corresponding to a central graphical element. I use the term “defined combination” to refer to any combination of independent keys that corresponds to a combination key, as interpreted by an associated device. Conversely, an “undefined combination” is a set of independent keys that do not, when simultaneously depressed, correspond to a defined combination key.
Thus, an IACK keypad is a keypad that includes both independent and combination keys or key regions. Such keypads typically have independent key regions identified by graphical elements on surfaces slightly elevated above adjacent surfaces carrying other graphical elements that identify combination key regions, for example. It is possible to design such keypads with advantageously very small spacing between adjacent independent key regions.
It is desirable to increase the accuracy of IACK keypads and other input devices with respect to the interpretation of the intent of the user, regardless of the switch technology used. There is a special need to better determine whether the user intends an individual or a combination key output in an IACK keypad, in those implementations when a strong tactile feedback is desired, such as is provided by metal snap domes. Improvements in the ergonomics of such keyboards are also desired, as well as better algorithms to simplify the interpretation of input, such as for use in telephones and such.
Additional improvements in the design and implementation of keypads and other input devices are desired.